By the Numbers: Internal Revenue Service

By Amy Roberts, CNN Library

Updated 9:16 PM ET, Mon June 3, 2013

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – IRS Commissioner John Koskinen is facing tough questions about an unknown number of missing agency e-mails due to hard drive crashes. Republicans are especially interested in e-mails belonging to former IRS official Lois Lerner as lawmakers investigate the agency's targeting of conservative tax-exempt groups.

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – Lois Lerner is sworn in before testifying to the House Oversight and Government Reform Committee in May 2013. As the former IRS director of exempt organizations, Lerner headed the division involved in targeting conservative groups. She invoked her constitutional right against self-incrimination and refused to answer questions from the congressional committee.

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – Sens. Max Baucus, left, and Orrin Hatch, co-chairmen of the Senate Finance Committee, confer in Washington in May 2013, during a hearing regarding the targeting of conservative groups.

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – Former IRS Commissioner Douglas Shulman is sworn in prior to testifying before the Senate Finance Committee in May 2013. Shulman was at the helm of the IRS during most of the period that agents were targeting conservative groups. Shulman denied full awareness of what was happening at the time, saying subordinates failed to inform him of the details.

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Key players in the IRS scandal – Rep. Darrell Issa, chairman of the House Oversight Committee, has held multiple hearings on the IRS controversy.

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Key players in the IRS scandal – Steve Miller, former acting commissioner of the IRS, testifies before the House Ways and Means Committee in May 2013. The committee held a hearing to examine revelations that the IRS singled out for scrutiny conservative groups seeking tax-exempt status.

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – Rep. Dave Camp, chairman of the House Ways and Means Committee, is among the GOP members who have sought to depict the controversy as government gone wild, with the IRS abusing conservative groups and other political foes of the administration.

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Key players in the IRS scandal – U.S. Attorney General Eric Holder testifies during a hearing of the House Judiciary Committee in May 2013. The day before, Holder announced a Justice Department investigation into any possible criminal wrongdoing by the IRS.

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Key players in the IRS scandal – Former acting IRS Commissioner Daniel Werfel, left, testifies before the House Financial and General Government Subcommittee with Treasury Inspector General for Tax Administration J. Russell George, right, in June 2013.

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Photos:Photos: Key players in the IRS scandal

Key players in the IRS scandal – Treasury Inspector General for Tax Administration J. Russell George is sworn in before testifying in Washington in May 2013. According to his report, the IRS developed and followed a faulty policy for determining whether applicants were engaged in political activities, which would disqualify the groups from receiving tax-exempt status.

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Story highlights

76 - Percentage in a recent poll who said a special prosecutor should be appointed to investigate the IRS

$2,524,320,134,000 - Total taxes collected by the IRS in fiscal year 2012

3,357- Applications received by the IRS in fiscal year 2012 for 501(c)(4) tax-exempt status

121 days - The IRS's overall goal for completing each application for tax-exempt status

The controversy over the Internal Revenue Service's targeting of conservative groups seeking tax-exempt status is back in the headlines with two hearings this week.

The House Appropriations Subcommittee on Financial Services held a hearing Monday where the Treasury inspector general for the IRS testified and Daniel Werfel, the embattled agency's new acting commissioner, appeared before Congress for the first time since taking over the agency at President Barack Obama's request. Tuesday, the House Ways and Means Committee will hear from groups who say they were targeted.